The Present Application relates generally to an optical connector assembly and both a cable and a plug for use with an optical connector assembly, and, more particularly, to an optical connector assembly having a high bendability and a small width.
In an electronic device such as a personal computer, a cellular phone, a personal digital assistant (PDA), a digital camera, a video camera, a music player, a game machine or a car navigation device, in order to realize both a decrease in an overall size of a casing thereof and an increase in the size of a display screen thereof, the casing may be configured to be collapsible. In such a case, a flexible printed circuit (FPC) and conductive wires such, as a fine coaxial cable, are arranged so as to pass through an inside of a hinge portion that allows a casing to be pivotably connected with another casing so that signals can be transmitted parallelly.
Although a signal transmission speed is increased in response an image resolution increase, since there is a limit in increasing the inside dimension of the hinge portion, it is practically impossible to arrange a conductive wire having a large width or diameter thereof. In addition, when a countermeasure against electromagnetic interference (EMI) is provided, the conductive wire will become larger in the width or diameter thereof.
In this regard, methods have been studied in which an optical waveguide capable of transmitting a large amount of signals and providing an excellent EMI countermeasure is integrated with conductive wires. One example can be found at Japanese Patent Application No. 2009-069203, the contents of which are fully incorporated herein in its entirety.
Additionally, FIG. 7 is a perspective view of a conventional cable assembly, having integrated therein conductive wires and an optical waveguide. As illustrated in FIG. 7, cable 901 includes an optical waveguide section and a conductive wire section. The optical waveguide section is provided with plurality of optical waveguide cores 911, arranged in parallel on lower base member 924, and cladding 912, formed so as to surround the surroundings of optical waveguide cores 911. The conductive wire section is provided with plurality of conductive wires 951, arranged in parallel on upper base member 923, and insulating layer 921, formed so as to surround the surroundings of conductive wires 951. Upper base member 923 is arranged on cladding 912, whereby cable 901 has a two-layer structure having the conductive wire section overlaps on the optical waveguide section.
Additionally, an end portion of cable 901 has an oblique and stair-like shape. The end portion is connected to a non-illustrated circuit board, and 45° slope surface 913 functions as a reflecting surface for optical coupling with an optical element on the circuit board. Moreover, upper surfaces 952 of conductive wires 951 function as an electrode surface bonded with the end of a conductive line which is connected to an electronic device on the circuit board. In this way, the optical waveguide section and the conductive wire section of cable 901 can be connected to the optical element and the electronic device on the circuit board, respectively.
However, since optical waveguide cores 911 and conductive wires 951 are arranged so as to overlap vertically with each other, the bendability of conventional cable 901 is low. For this reason, it is difficult for cable 901 to be used as the wiring within a small electronic device where there is little empty space and, accordingly, wiring paths become complex. Additionally, the bendability of cable 901 may be improved when the width of cable 901 is increased so that optical waveguide cores 911 and conductive wires 951 are arranged to not overlap vertically. However, when the width of cable 901 is increased, it becomes more difficult for cable 901 to be used as the wiring within a small-size electronic device or apparatus having little empty space. Particularly, when a cable-side connector is connected to the front end of cable 901 so that the cable-side connector is engaged to a board-side connector mounted on a circuit board, the width of the cable-side connector will inevitably be larger than the width of cable 901. Therefore, the overall size of a connector assembly including the board-side connector increases.